The present invention relates, in general, to factory assembled boilers for steam and/or electric power generation, also referred to as package boilers, and particularly to a new package boiler assembly having a low NO.sub.x integrated boiler-burner apparatus which employs a multiple nozzle burner array in its inlet windbox, and other features which improve its operation.
Multiple nozzle array burners (often referred to as duct burners) are known as are package boilers which are designed for factory assembly. See, for example U.S. Pat. Nos. 4,462,795 and 3,173,523. A particularly successful package boiler design is known as the FM Package Boiler manufactured by The Babcock & Wilcox Company and disclosed in the publication Steam: its generation and use, 40th Edition page 25-8. Other types of package boilers include what are known as "F" type boilers, particularly the PFI (Power for Industry) and PFT (Power for Turbine) types described in Steam: its generation and use, 39th Edition, Chapter 25, pages 25-8 and 25-9. Also known are the "Three Drum Waste Heat Boilers" shown on page 27-10, FIG. 10, of Steam: its generation and use, 39th Edition, and on page 31-8 of Steam: its generation and use, 40th Edition. This latter type of boiler is also known as an "FO" type, and in the industry as simply an "O" type boiler.
The use of supplemental cooling tubes in the inlet area of a boiler furnace is also known. See for example, U.S. Pat. No. 2,653,447. Additionally, water cooled surface in the form of division walls or wing walls have been supplied on many boilers to increase heat absorption and reduce furnace temperatures. The use of staging air for NO.sub.x reduction through sidewall ports in package boilers is also known.
The use of fins in an inlet duct with burners is also disclosed in U.S. Pat. No. 3,781,162. Also see U.S. Pat. No. 4,767,319 for various baffles and control surfaces to help distribute heat in a duct burner arrangement.